Method of manufacturing a motor rotor

ABSTRACT

A method of manufacturing a motor rotor includes a preparing step, a pre-heating step and a molding step. The preparing step includes preparing multiple silicon-steel sheets, a shaft, a mold and a molten copper liquid. The pre-heating step includes stacking the silicon-steel sheets and mounting the stacked silicon-steel sheets around the shaft and pre-heating the silicon-steel sheets to a specific temperature. The molding step includes mounting the silicon-steel sheets and the shaft into the mold, heating the silicon-steel sheets, the shaft and the mold, drawing air out of the mold to a vacuum status, injecting the molten copper liquid into the mold, sucking the molten copper liquid and filling up the mold with the molten copper liquid, cooling the mold to form a copper ring around the silicon-steel sheets, getting the shaft and the silicon-steel sheets with the copper ring out of the mold and separating the shaft from the silicon-steel sheets to form a motor rotor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manufacturing method, and more particularly relates to a method of manufacturing a motor rotor that can increase the yield rate of motor rotor production.

2. Description of Related Art

A conventional method of manufacturing a motor rotor includes preparing multiple silicon-steel sheets, stacking and holding the silicon-steel sheets by mounting the silicon-steel sheets around a shaft, heating the silicon-steel sheets and the shaft, putting the silicon-steel sheets and the shaft into a mold after heating, injecting a molten copper liquid into the mold to form a copper ring around the silicon-steel sheets, opening the mold after cooling and taking the silicon-steel sheets and the shaft with the copper ring out of the mold. Then, the shaft is separated from the silicon-steel sheets and the copper ring, and a motor rotor is manufactured.

The conventional method of manufacturing a motor rotor can form a copper ring around the silicon-steel sheets, as the molten copper liquid flows into and fills up the mold between the silicon-steel sheets by the flowage of the molten copper liquid to form the copper ring. However, the flowing speed of the molten copper liquid is slow and this will increase the time of manufacturing the copper ring. In addition, the molten copper liquid may not be able to fill up the mold completely to form a whole copper ring around the silicon-steel sheets and this will increase the reject ratio of motor rotor manufacturing.

Therefore, the present invention provides a method of manufacturing a motor rotor to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a method of manufacturing a motor rotor that can increase the yield rate of motor rotor production.

The method of manufacturing a motor rotor in accordance with the present invention includes a preparing step, a pre-heating step and a molding step. The preparing step includes preparing multiple silicon-steel sheets, a shaft, a mold and a molten copper liquid. The pre-heating step includes stacking the silicon-steel sheets, mounting the stacked silicon-steel sheets around the shaft and pre-heating the silicon-steel sheets and the shaft to a specific temperature. The molding step includes mounting the silicon-steel sheets and the shaft into the mold, heating the silicon-steel sheets, the shaft and the mold, drawing air out of the mold to keep the mold at a vacuum status, injecting the molten copper liquid into the mold, sucking the molten copper liquid and filling up the mold with the molten copper liquid by the vacuum status of the mold, cooling the mold to form a copper ring around the silicon-steel sheets, getting the shaft and the silicon-steel sheets with the copper ring out of the mold, cooling the shaft and the silicon-steel sheets with the copper ring to room temperature and separating the shaft from the silicon-steel sheets to form a motor rotor.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a method of manufacturing a motor rotor in accordance with the present invention;

FIGS. 2 and 3 are operational perspective views of stacking multiple silicon-steel sheets of a motor rotor in accordance with the present invention;

FIG. 4 is an operational exploded perspective view of mounting the silicon-steel sheets of the motor rotor in FIG. 3 around a shaft;

FIG. 5 is an operational side view in partial section of mounting the silicon-steel sheets and the shaft of the motor rotor in FIG. 4 into a mold;

FIG. 6 is an operational side view in partial section of drawing air out of the mold in FIG. 5;

FIG. 7 is an operational side view in partial section of injecting a molten cooper liquid into the mold in FIG. 6 to form a copper ring around the silicon-steel sheets;

FIG. 8 is an operational side view in partial section of separating the silicon-steel sheets, the shaft and the cooper ring from the mold in FIG. 7;

FIG. 9 is a perspective view of the silicon-steel sheets, the shaft and the cooper ring in FIG. 8; and

FIG. 10 is a perspective view of a motor rotor with the silicon-steel sheets and the copper ring in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1 to 5 and 7, a method of manufacturing a motor rotor in accordance with the present invention comprises a preparing step, a pre-heating step, a molding step and a forming step.

The preparing step comprises preparing multiple silicon-steel sheets 10, a shaft 20, a mold 30, a molten copper liquid 40 and a surface-treating device. Each silicon-steel sheet 10 has a center, a shaft hole 11 and multiple copper holes 12. The shaft hole 11 is formed through the center of the silicon-steel sheet 10. The copper holes 12 are formed through the silicon-steel sheet 10 at intervals around the shaft hole 11. The shaft 20 has two free ends, two connecting holes 21, two holding panels 23 and two fasteners 22. The connecting holes 21 are respectively formed in the free ends of the shaft 20. The holding panels 23 respectively abut the free ends of the shaft 20. The fasteners 22 are respectively mounted through the holding panels 23 and are respectively connected to the connecting holes 21 to hold the holding panels 23 on the shaft 20. The mold 30 has a front end, a rear end, an injecting hole 31 and a drafting hole 32. The injecting hole 31 is formed in the front end of the mold 30. The drafting hole 32 is formed in the rear end of the mold 30. The surface-treating device can be a cutting machine or a grinding machine.

With reference to FIGS. 2, 3 and 4, the pre-heating step comprises stacking the silicon-steel sheets 10, mounting the stacked silicon-steel sheets 10 around the shaft 20 by the shaft holes 11, holding the silicon-steel sheets 10 on the shaft 20 by the holding panels 23 and the fasteners 22, pre-heating the silicon-steel sheets 10 and the shaft 20 for 10-30 minutes to a temperature between 200° C. and 500° C.

With reference to FIGS. 5 to 9, the molding step comprises mounting the silicon-steel sheets 10 and the shaft 20 into the mold 30 between the injecting hole 31 and the drafting hole 32 after heating, heating the silicon-steel sheets 10, the shaft 20 and the mold 30 for an hour to keep the temperature at between 200° C. and 500° C., drawing air out of the mold 30 via the drafting hole 32 to keep the mold 30 at a vacuum status, injecting the molten copper liquid 40 into the mold 30 via the injecting hole 31, sucking the molten copper liquid 40 and filling up the mold 30 and the copper holes 12 of the silicon-steel sheets 10 with the molten copper liquid 40 by the vacuum status of the mold 30, cooling the mold 30 after the molten copper liquid 40 fills up the mold 30 to form a copper ring 60 around the silicon-steel sheets 10, getting the shaft 20 and the silicon-steel sheets 10 with the copper ring 60 out of the mold 30 when the temperature of the mold 30 is cooled down to 700° C.-800° C. and cooling the shaft 20 and the silicon-steel sheets 10 with the copper ring 60 to room temperature. Preferably, the temperature of the molten copper liquid 40 is kept at between 1200° C. and 1500° C.

The forming step comprises surfacing the copper ring 60 by the surface-treating device after cooling the shaft 20 and the silicon-steel sheets 10 with the copper ring 60 to room temperature and separating the shaft 20 from the silicon-steel sheets 10 by loosening the fasteners 22 to form the motor rotor as shown in FIG. 10.

In use, the method of manufacturing a motor rotor in accordance with the present invention is drawing air out of the mold 30 to make the mold 30 maintain the vacuum status, and the molten copper liquid 40 can be sucked to fill up the mold 30 and the cooper holes 12 of the silicon-steel sheets 10 by the vacuum status of the mold 30 to form the whole and complete cooper ring 60 around the silicon-steel sheets 10. Then, the yield rate of the production of the cooper ring 60 around the silicon-steel sheets 10 of the motor rotor can be increased. In addition, the flowing speed of the molten copper liquid 40 can be increased by a sucking force provided by the vacuum status of the mold 30 and this can shorten the time of manufacturing the copper ring 60 of the motor rotor.

Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A method of manufacturing a motor rotor comprising: a preparing step comprising: preparing multiple silicon-steel sheets and each silicon-steel sheet having a center, a shaft hole formed through the center of the silicon-steel sheet and multiple copper holes formed through the silicon-steel sheet at intervals around the shaft hole; preparing a shaft with two free ends; preparing a mold with a front end, a rear end, an injecting hole formed in the front end of the mold and a drafting hole formed in the rear end of the mold; and preparing a molten copper liquid and keeping the temperature of the molten copper liquid at between 1200° C. and 1500° C.; a pre-heating step comprising: stacking the silicon-steel sheets; mounting the stacked silicon-steel sheets around the shaft by the shaft holes; and pre-heating the silicon-steel sheets and the shaft for 10-30 minutes to a temperature between 200° C. and 500° C.; and a molding step comprising: mounting the silicon-steel sheets and the shaft into the mold between the injecting hole and the drafting hole after heating to the temperature between 200° C. and 500° C.; heating the silicon-steel sheets, the shaft and the mold for an hour to keep the temperature at between 200° C. and 500° C.; drawing air out of the mold via the drafting hole to keep the mold at a vacuum status; injecting the molten copper liquid into the mold via the injecting hole; sucking the molten copper liquid and filling up the mold and the copper holes of the silicon-steel sheets with the molten copper liquid by the vacuum status of the mold; cooling the mold after the molten copper liquid fills up the mold to form a copper ring around the silicon-steel sheets; getting the shaft and the silicon-steel sheets with the copper ring out of the mold when the temperature of the mold is cooled down to 700° C. to 800° C.; cooling the shaft and the silicon-steel sheets with the copper ring to room temperature; and separating the shaft from the silicon-steel sheets to form the motor rotor. 2-5. (canceled)
 6. The method of manufacturing a motor rotor as claimed in claim 1, wherein the preparing step comprises preparing a surface-treating device; and the method of manufacturing a motor rotor comprises a forming step after the molding step, and the forming step comprises surfacing the copper ring by the surface-treating device after cooling the shaft and the silicon-steel sheets with the copper ring to room temperature.
 7. The method of manufacturing a motor rotor as claimed in claim 6, wherein the preparing step comprises preparing the shaft with two connecting holes respectively formed in the free ends of the shaft, two holding panels respectively abutting the free ends of the shaft and two fasteners respectively mounted through the holding panels and respectively connected to the connecting holes to hold the holding panels on the shaft; the pre-heating step comprises holding the silicon-steel sheets on the shaft by the holding panels and the fasteners before pre-heating the silicon-steel sheets and the shaft; and the forming step comprises separating the shaft from the silicon-steel sheets by loosening the fasteners to form the motor rotor.
 8. The method of manufacturing a motor rotor as claimed in claim 7, wherein the surface-treating device is a cutting machine to surface the copper ring.
 9. The method of manufacturing a motor rotor as claimed in claim 7, wherein the surface-treating device is a grinding machine to surface the copper ring. 10-11. (canceled) 